Capstone Project: Obesity

MPH510 Applied Epidemiology

Becky Olomon

October 25, 2013 Background:

General information: Overweight or obese is defined as having an abnormal or excessive accumulation of body fat, which puts a person's health at increased risk (WHO 2013). Obesity, once considered a health issue afflicting mainly the United States and other affluent countries, has spread across the globe in the last few decades. International obesity rates have doubled since 1980, with 35% of adults worldwide being overweight and 11% obese (WHO 2013). Sixty-five percent of the world's population lives in countries where obesity contributes to more deaths than malnutrition (WHO 2013).

Being overweight or obese is a risk factor for cardiovascular disease, diabetes, musculoskeletal disorders and some cancers. These risks are increased if the subject's fat is deposited primarily in the visceral (abdominal) area. Being overweight or obese is the fifth leading contributor to deaths globally (WHO 2013). Many national and regional governments and healthcare agencies are conducting screening programs in their areas to try and curb this trend.

Selecting a methodology and conducting screens can be extremely problematic as well.

There are many facets to obesity that complicate screening. Obesity is a very emotionally- charged subject. Many people do not want to be screened, already knowing their weight is over the recommended standards. Many people avoid being screened so that others will not see or know their true weight (O'Dea 2004). Many people do not trust popular screening methods because they are aware measurements do not take muscle verses fat mass into account. No other medical screenings have as much of a debate over testing and treatment methods. This poses a unique set of challenges for those trying to screen and treat obesity. Common screening tests for Obesity: There are a multitude of ways to test the body fat ratio of a person, each with a long list of pros and cons. Hydrostatic weighing is considered the gold standard for body fat analysis; however, this method requires the use of highly trained professionals and either a pool or tank in which to submerge the subject (CDC 2013). It is therefore not feasible for a majority of the population or testing large numbers of cases in a short amount of time. Dual-energy x-ray absorptiometry (DXA) is a testing method that uses low levels of radiation. DXA testing measures BMI in conjunction with bone density measurements. This allows researchers to explore correlations of age, weight, diet and bone health (CDC 2007). It is sometimes used by those conducting the NHANES survey and other researchers. This is also the preferred screening method for medical professionals who want to examine the exact location of fat within the abdominal area to determent the how much of a health risk it is posing for the subject (Despres 1998). However, like hydrostatic weighing, this testing is not feasible for most screening situations due to the machines' large size and cost.

BMI is the most common test used for measuring obesity due to the ease with which it can be conducted. To calculate BMI for adults, one divides a person's weight in kilograms by the square of his or her height in meters (WHO 2013). For children, these measurements are adjusted by age.

The US Preventative Services Task Force, a branch of the government dedicated to improving public health, recommends that clinicians test the BMI of all adult patients for obesity (2013).

According to the USPSTF, BMI is reliable and valid for identifying those at increased risk for health issues related to obesity. Many experts believe that the location of the fat tissue is also critical to calculate the risk associated with increased weight, and encourage waist measurements as well.

There are debates as to which waist measurement or ratio (waist alone, weight verses height or weight verses hip ratios) is the best predictor of risk. Measurements of specificity, sensitivity, PV+ and PV- :

Hydrostatic weighing: Is the gold standard. This is the diagnostic test by which the true and false positives, as well as, the true and false negatives are determined.

Dual-Energy X-ray Absorptiometry: DXA testing is also held to a high standard and is a method by which other screening techniques are judged. One study showed it to be highly accurate when underweight patients were tested repeatedly and their weight supplemented with lard packets

(See Table 2) (Hadersleve, Hadersleve and Staun 2005). DXA testing is capable of detecting even small changes in body fat ratios for underweight patients.

BMI: When compared for sensitivity and specificity, some have found BMI testing is an acceptable and more feasible alternative to DXA testing (Lazarus 2013). One study evaluating 32 different samples, totally almost 32,000 subject, concluded that BMI had a pooled sensitivity of 0.50 (a 95% confidence interval) and a pooled specificity of 0.90 (Okorodudu et al 2010). This means, unfortunately, that the high specificity causes a failure to identify approximately half of the people with excess body fat. Okorodudu's study reported the likelihood ratios for BMI testing as "Positive

LR was 5.88 (CI: 4.24–8.15), 97.8%; the negative LR was 0.43 (CI: 0.37–0.50)" (2010). For child and adolescent ratings, see Table 1. Setting BMI recommendations to the 85th percentile is the most recommended point for defining excess body fat (Lazarus 2013). However, depending on the emphasis of the screeners (specificity verses sensitivity) this can be adjusted accordingly.

Another study compared the different methods of waist measuring and ratios for accuracy.

The researchers found that when compared to BXA testing, waist circumference alone had a specificity of 89% for girls and 87% for boys who had a high trunk fat mass. The specificity of waist circumference measurements when using the 80th percentile standard was 94% for girls and 92% for boys (Taylor et al 2000). They concluded that waist circumference measurements are an effective measure of abdominally obesity.

Populations/ settings for whom these screening tests are commonly used:

BMI testing is conducted on cases of sexes, all ages, and all ethnicities. There are a few variations on the screenings for different cases, however. Screening children is more complicated than adults and age factors must be taken into consideration (CDC 2013). Elderly case can have distorted results with certain types of tests, such as DXA, due to hydration levels and bone density differences.

The US Preventative Services Task Force recommends that all adults be screened by their clinicians yearly (2003). BMI screenings are frequently offered at public health fairs, employee health fairs, and by fitness facilities. DXA testing is most often conducted by clinicians when a bone density test is also desired or researchers want more accurate tests for their research.

Subjects rarely receive a DXA test for body composition analysis alone (CDC 2007). Hydrostatic weighing is most often conducted at universities, research facilities and upscale fitness centers.

There is an emerging industry that brings the most accurate body composition testing possible to the general public. Some companies now have a method of hydrostatic weighing in a portable tank transported by truck. While expensive, a public who is desperate for accurate information is willing to pay the price.

Ethical considerations as a public health professional / epidemiologist: Have, Beaufort, Teixeira, Mackenbach and Heide reviewed 60 interventions for obesity for ethical concerns (2010). The first principle of ethics is to "do no harm." Unfortunately, in trying to do good, it is easy to do harm with overweight or obese subjects. Well intentioned messages to young women and men have been received in a manner which leads to distorted body images and eating disorders (O'Dea 2004). Overweight adolescents are frequently bullied and assumed to have unattractive character traits by their peers and teachers, such as laziness or stupidity (Have Et al

2010). These children are usually already aware of their weight issue and have poor self esteem.

Health care professionals should also be aware of their own views and previously held beliefs on overweight individuals can affect their behavior towards and treatment of their patients (O' Dea

2004). Negative beliefs lead to discrimination, even if unintentional. Improper advice and information may be given to clients due to these prejudices (O'Dea 2004). There are also certain professions (military or airline stewardess) that will terminate the employment of someone who does not meet a certain weight standard. Not keeping the screening results confidential could be extremely harmful to the livelihood of these individuals. Overweight people, particularly women are more likely to avoid any type of medical care, for fear that they will be lectured on their weight when they visit healthcare providers (O'Dea 2004).

There is also a concern that some obesity initiatives conflict with the public health principle of justice and equality (Have Et Al 2010). Screening programs also must be careful to not discriminate against certain sections of society based on socio-economic status. Those who develop screening programs and interventions need to remember that many of those with weight issues have less income and availability to weight-loss resources. Obesity screenings and interventions are frequently biased against poorer people. Certain minorities may be uncomfortable with the facilities provided for exercise, due to religious doctrines. Researchers need to be culturally sensitive when developing screening programs and initiates (Have Et Al 2010). Another possible ethics problem regarding obesity screenings is the risk of publisher bias.

Publication bias is the tendency of a study's results to be influenced by the possibility of publication

(Friis and Sellers 2013). Editors have a tendency to prefer to publish studies that show expected good performances of BMI testing, which can result in a researcher overestimating the real diagnostic performance of the screening (Okorodudu 2010). This results in an overabundance of false positives in the available literature and a misunderstanding of the issue being studied or measured. This is especially true for obesity, which is a very popular topic and one with a preponderance of conflicting studies. Researchers should strive to tell the truth as closely as possible, and avoid being overzealous of their results.

Recommendations:

 What screening test would you recommend for your city/state and for what target population

and in what setting. Why?

While the sensitivity of BMI testing is lower than is to be desired, it is still the most feasible recommendation for the majority of Georgia. More subjects with excess fat could also be detected if the sensitivity of screenings was increased and some specificity was sacrificed. These tests are simple to administer, and screeners could be easily trained. Conducting weight and waist circumference measurements is quick, and equipment for the screening is very inexpensive. When faced with the large number of people in our state who need to be screened and the limited funding that would be allotted for a program such as this, time, cost and ease are important factors.

There are multiple reasons why conducting waist circumference measurements should be done with BMI screening. This would better identify those cases that are at increased risk for negative health effects from obesity. In multiple tests, it has been shown that the screenings conducted individually do not have enough of a confidence interval. Ashwell found that 35% of men and 14% of women who had a BMI below 25 kg/m2 were indeed at increased risk for health problems due to the fat being located primarily in their abdomen (2009). This means that without a waist measurement component to the testing, 17% of the total male population and 6% of the total female population that is screened would be overlooked as at risk. Also, while much of the population has heard through popular media that BMI testing is not very accurate, they have also heard that fat deposits located abdominally are more harmful that other distributions. By including a waist measurement component, screeners will have more information with which to convince subjects who need to seek out assistance to do so.

A large number of the population is now aware that BMI does not take muscle mass verses adipose mass into account. Therefore, a great many people discount the validity of the test as applicable to them. These people believe that they are simply "big boned" or muscular and make little or no attempt to change their weight. http://www.nature.com/ijo/journal/v29/n2/full/0802867a.html

 How you would you go about increasing the participation levels in the screening? Camilloni et al found in their review of various participation increasing strategies that while postal reminders did have a small positive effect, telephone calls were more effective (2013). They also found a relationship between the detail and length of the letters participation. Longer letters tend to discourage some with lower education levels (a type of SES discrimination). Having an actual appointment day and time verses being able to walk in at any time also seems to have more positive results for people actually attending the screenings.

Weight loss is a very popular topic in our nation. Americans spend billions of dollars each year on diet foods, counseling sessions, creams, pills and "quick fixes". An excellent incentive would be to offer some weight loss services at the screening. If the program administrator could arrange the presence of a dietician, a behavioral modification councilor and/or a personal trainer, participants would be more likely to participate with the incentive of free help to follow their screening.

 What role should public health play in increasing screening participation e.g. but not limited

to education, funding, access, etc.?

Public health initiatives need to begin by removing some of the stigma around overweight and obesity. Public health professionals have been trailblazers and advocates against oppressed populations, including ethic minorities, those with disabilities, and the GLBT population.

Obesity is one of the last socially acceptable biases. Those with a weight problem are frequently assumed to be lazy, incompetent, have poor impulse control and unfriendly. Many overweight and obese people do not seek help, because to be stigmatized would be psychologically traumatizing and possibly socially devastating. Public health initiatives need to begin by training health workers to recognize the impact their behavior and biases can create with these patients (Lawrence, Hazlett and Abel 2012). Any public education initiatives need to incorporate an understanding of the factors associated with obesity and eliminate oppression (Lawrence, Hazlett and Abel 2012). Hopefully the movement will continue to grow to advocate "health at any size", remove emphasis on weight and increase emphasis on health behaviors (O'Dea 2004).

Secondly, public health entities need to combat the bombardment of false information being fed to the public. The public is presented with false information about appropriate weights and sizes from the popular media. Young girls and boys are at risk for developing eating disorders and being underweight from the messages they receive. Outrageous claims from sellers of weight loss products are very confusing and lead people to not be screened and perhaps. Legislation needs to be enacted to regulate the claims of supplements, diet plans and exercise regiments. These items need to be screened for safety. Public health officials need to advocate on behalf of the public to receive the best information scientifically available regarding who has a problem with excess fat and how they should address that problem.

Public health entities need to also work to ensure that obesity does not become more of a health disparity than it already is. Health disparities are those social, economic and environmental factors that put persons at a disadvantage for positive health outcomes (Friis and

Sellers 2013). A correlation between lower SES and being overweight or obese is well documented.

Those with a lower SES have less knowledge, time, expendable income, and available facilities with which to combat their weight problems. Those of lower SES are already at a higher risk for diseases correlated with obesity, such as diabetes and heart disease (Friis and Sellers 2013). Public health advocates need to focus on these populations to bring greater equality to healthcare in our country. Ashwell, Margaret. Gibson, Sigrid. (March 31, 2009) Waist to Height Ratio is a simple and Effective

Obesity Screening tool for cardiovascular risk Factors: Analysis of Data from the British

National Diet and Nutrition Survey of Adults Aged 19-64 Years. Obesity Facts-The European

Journal of Obesity. Retrieved from http://www.karger.com/Article/Pdf/203363

Camilloni, Laura. Et al. (2013). Methods to increase participation in organized screening programs: a

systematic review. BMC Public Health. Retrieved from

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JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=ap h&AN=88981762

Despres, Jean-Pierre. (April 1998). The Insulin Resistance-Dyslipidiemic Syndrome of Visceral

Obesity: Effect on Patient's risk. Obesity Research. Retrieved from

http://onlinelibrary.wiley.com/doi/10.1002/j.1550-8528.1998.tb00683.x/pdf

Friis, Robert H. Seller, Thomas A. (2013). Epidemiology for Public Health Practice. Jones and Bartlett

Learning. Burlington, MA.

Have, M. Beaufort, I.D. Teixeira, P.J. Mackenbach, J.P. Van der Heide, A. (October 2010). Ethics and

prevention of overweight and obesity: an inventory. Obesity Reviews. Retrieved from

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Lawrence, Shawn A. Hazlett, Rebekah. Abel, Eileen M. (February 2012). Obesity Related Stigma as a

Form of Oppression: Implications for Social Work Education. Social Work Education. Retrieved from http://web.ebscohost.com.vproxy.cune.edu/ehost/pdfviewer/pdfviewer? sid=c56a48d8-68c1-4590- 9b89-f36a7ceb3bb3%40sessionmgr13&vid=7&hid=10

Lazarus, R. Baur, Louise. Webb, Karen. Blyth, Fiona. (October 2013). Body mass index in screening

for adiposity in children and adolescents: systematic evaluation using receiver operating

characteristic curves. The American Journal of Clinical Nutrition. Retrieved from

http://ajcn.nutrition.org/content/63/4/500.full.pdf+html

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Research. Retrieved from http://her.oxfordjournals.org/content/20/2/259.full

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http://www.cdc.gov/nchs/data/nhsr/nhsr025.pdf

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of waist circumference, waist-to-hip ratio and conicity index as screening tools for high trunk fat

mass, as measured by dual-energy X-ray. The American Journal of Clinical Nutrition.

Retrieved from http://ajcn.nutrition.org/content/72/2/490.full Unknown, Author. (October 17, 2013). Screening for Obesity in Adults: Recommendations and

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http://www.uspreventiveservicestaskforce.org/3rduspstf/obesity/obesrr.htm

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http://www.who.int/topics/obesity/en/ Table 1:

Comparison of the sensitivities and specificities (and 95% CIs) for detecting overweight at the 85th percentiles of BMI-for-age, RI (Rohrer index)-for-age, and weight-for-height in children aged 2–19 y with the use of the pooled data set and data from the third National Health and Nutrition Examination Survey (NHANES III; 31)

NHANES III Pooled data set Age and index Sensitivity Specificity Sensitivity Specificity 1 Only 3–5 y from the pooled data set. % % 2–5 y1 BMI-for-age 78.3 (74.6, 81.8) 88.3 (87.2, 89.4) 88.5 (69.8, 97.4) 79.4 (71.6, 85.9) RI-for-age 65.7 (61.4, 69.7) 90.8 (89.8, 91.7) 73.1 (52.2, 88.4) 91.9 (86.0, 95.5) Weight-for-height 74.6 (70.7, 78.3) 90.9 (89.9, 91.8) 88.5 (69.8, 97.4) 88.2 (81.6, 93.1) 6–11 y BMI-for-age 92.7 (90.5, 94.6) 91.5 (90.4, 92.6) 98.6 (92.4, 99.8) 67.7 (62.8, 72.3) RI-for-age 87.9 (85.1, 90.2) 91.1 (90.0, 92.2) 97.2 (90.2, 99.6) 68.4 (63.6, 73.0) Weight-for-height 83.9 (80.9, 86.5) 92.6 (91.5, 93.6) 95.8 (88.1, 99.1) 70.8 (66.1, 75.3) 12–19 y BMI-for-age 84.7 (81.8, 87.3) 90.5 (89.2, 91.7) 100 (100, 100) 72.2 (66.2, 77.7) RI-for-age 82.3 (79.2, 85.0) 89.7 (88.4, 90.9) 100 (100, 100) 71.4 (65.3, 76.9) Weight-for-height 79.6 (76.4, 82.5) 90.3 (89.0, 91.5) 100 (100, 100) 74.4 (68.5, 79.7)

http://ajcn.nutrition.org/content/75/6/978.full

Table 2:

The actual weight and chemical composition of lard packets placed on the thighs and abdomen of 8 healthy lean male volunteers and the composition measured by DXA. Thighs Trunk

Mean ± Percentage Mass Detected Mean Mean ± Percentage Mass Detected Mean Actual 95% CI 95% CI SD ± SD SD ± SD

3.48 ± 3.34 ; 3.72 ± 3.57 ; Total mass (kg) 3.49 99.7 ± 4.9 106.6 ± 5.1 0.17 3.62 0.18 3.87

Soft-tissue mass 3.48 ± 3.33 ; 3.66 ± 3.50 ; 3.49 99.6 ± 5.2 104.9 ± 5.5 (kg) 0.18 3.63 0.19 3.82

1.92 ± 0.97 ; 1.42 ± 0.65 ; Fat mass (kg) 1.82 105.2 ± 62.3 77.9 ± 50.8 1.13 2.86 0.92 2.19

Lean-tissue mass 1.56 ± 0.59 ; 2.24 ± 1.44 ; 1.67 93.5 ± 69.5 134.3 ± 57.3 (kg) 1.16 2.53 0.96 3.04

(Hadersleve, Haderslev and Staun 2005)